Is Ozempic dangerous?

The short answer

Under the supervision of a BIG-registered doctor and with the correct indication, Ozempic is a relatively safe medicine with a favourable risk profile. Most patients experience mild gastrointestinal side effects that disappear within 4-12 weeks. Serious side effects exist but are rare, comparable to or lower than many other chronic medications such as blood pressure medication or statins.

Untreated obesity itself is a much greater health risk than Ozempic. The SELECT trial from 2023 in more than 17,000 cardiac patients showed that semaglutide (the active substance in Ozempic and Wegovy) lowers the risk of heart attack and stroke by 20%. Weighing the risks against the benefits, GLP-1 is a net improvement in health for most patients with a BMI ≥30.

The 'is Ozempic dangerous?' narrative in the media is often exaggerated by dramatic individual case reports without context. In this article we look at the real figures.

The real risks at a glance

EMA records all known side effects in the official product information. Here are the numbers that matter:

Very common (>10%): nausea 20-44%, diarrhoea 12-30%, constipation 10-25%, vomiting 10-24%. These are usually mild to moderate, occur during the titration phase (first 4-12 weeks) and are not life-threatening. Only 1-3% of patients stop because of these side effects.

Common (1-10%): headache, dizziness, fatigue, loss of taste, mild hypoglycaemia (only in combination with insulin or a sulfonylurea), allergic skin reaction at the injection site, dry mouth.

Rare (0.1-1%): acute pancreatitis (inflammation of the pancreas), gallbladder inflammation, gallstones due to rapid weight loss, worsening of existing diabetic retinopathy. Pancreatitis is the most feared side effect; the absolute incidence is 0.1-0.3% per year, comparable to the general population according to a large meta-analysis (BMJ 2023).

Very rare (<0.1%): severe hypoglycaemia without other blood-sugar medication, severe allergic reaction (anaphylaxis), gastroparesis / ileus (paralysed stomach), kidney damage from dehydration due to vomiting.

Theoretical (based on animal studies, not proven in humans): medullary thyroid carcinoma (MTC). EMA requires a warning for patients with a personal or family history of MTC or MEN2 syndrome. In non-MTC patients, no significantly increased MTC incidence has been demonstrated in 10 years of market use.

What EMA pharmacovigilance says

Since Ozempic entered the European market in 2017, EMA has collected all reported side effects via the EudraVigilance system. Up to May 2026, more than 1.5 million patient-years have been collected, allowing even very rare side effects to be analysed statistically.

Important conclusions from these data: the side-effect profile as described in the patient information leaflet is accurate, and no surprising new complications have emerged after market authorisation. The incidence of pancreatitis and gallbladder events is consistent with the figures from the SUSTAIN and STEP trials. There is no signal of increased cardiovascular mortality; in fact the opposite has been demonstrated in SELECT.

A specific point of attention is suicidal ideation: in 2023 EMA started an investigation into possibly increased reports of depression and suicidality. The conclusion in January 2024 was: no causal link demonstrable between GLP-1 medication and suicidal behaviour. The advice remains to monitor patients with severe depression or a history of suicidality when starting treatment.

SELECT trial: Ozempic lowers mortality

The SELECT trial (Lincoff et al., NEJM 2023) is the largest piece of evidence in the 'is Ozempic dangerous' debate. 17,604 patients with a BMI ≥27 and prior cardiovascular disease were randomised to Ozempic 2.4 mg (the same dose as Wegovy) or placebo, and followed for an average of 33 months.

The primary endpoint was major adverse cardiac events (MACE: heart attack, stroke, cardiovascular death). Result: 6.5% in the Ozempic group vs 8.0% in the placebo group. A relative risk reduction of 20%.

In addition: 19% reduction in all-cause mortality (death from any cause), 18% reduction in cardiovascular death, 28% reduction in kidney problems.

In other words: in patients with excess weight and prior cardiovascular disease, Ozempic demonstrably lowers the risk of death. This is one of the most robust pieces of evidence in modern pharmacology and has led to an extension of the Wegovy reimbursement indication to this patient group.

Comparison with other weight-loss options

To put 'dangerous' into context: compare Ozempic with the alternatives.

Bariatric surgery (gastric reduction, gastric bypass): 0.1-0.5% mortality within 30 days of surgery. Risk of malabsorption, dumping syndrome, weight regain in around 20-30% within 10 years. Effectiveness: 25-35% weight loss.

Older weight-loss medication: sibutramine (Reductil) was withdrawn from the market in 2010 because of a 16% increased risk of heart attacks and strokes. The fen-phen combination (fenfluramine/phentermine) was withdrawn in 1997 because of heart valve problems in 30% of users. Orlistat (Xenical/Alli) is still available but gives only 3-5% weight loss with unpleasant side effects (fatty diarrhoea, vitamin deficiencies).

Crash diets and very-low-calorie diets: cardiac arrhythmias from malnutrition, gallstones from rapid weight loss (incidence up to 25%), loss of muscle mass and metabolic deterioration. Long-term effectiveness: usually 80-90% weight regain within 5 years.

Untreated obesity itself: 13 years lower life expectancy at BMI ≥40 (Lancet 2009 meta-analysis), 2-3× increased risk of type 2 diabetes, 50% increased risk of cardiovascular disease, 40% increased risk of several types of cancer.

Against that background, Ozempic is a relatively mild and proven effective intervention.

When it does become dangerous

There are specific situations in which Ozempic use does carry increased risk. We want to name these explicitly.

Personal or family history of MTC or MEN2: absolute contraindication. Always ask about thyroid cancer in the family history.

Active pancreatitis or recent (<12 months) pancreatitis: do not start, or stop.

Pregnancy and breastfeeding: stop at least 2 months before conception. Read our article on GLP-1 and pregnancy.

Combination with insulin or a sulfonylurea (glimepiride, gliclazide): risk of severe hypoglycaemia. When starting GLP-1, the dose of those other medicines is usually lowered.

Severe gastroparesis (delayed gastric emptying): GLP-1 makes this worse.

History of an eating disorder (anorexia, bulimia): prescribe with great caution, usually only in specialised settings with psychotherapeutic support.

Increasing the dose too quickly: increases the risk of severe nausea, vomiting and dehydration. Always follow the 4-week titration schedule.

Grey-market Ozempic: the real danger

The real 'is Ozempic dangerous' story is often about counterfeit or grey-market Ozempic, not the genuine EMA-approved version. Since 2023 there have been several warnings from EMA and the Dutch Medicines Evaluation Board (CBG) about counterfeit pens.

Concrete risks of the grey market: unknown concentration (often much higher or lower than the label), no sterility (risk of infection on injection), incorrect storage during transport (degraded peptide), false identification of the active substance (insulin has sometimes been found in counterfeit Ozempic, with life-threatening consequences), no medical screening for contraindications.

In 2023-2024, several cases of hypoglycaemic shock due to counterfeit Ozempic were reported in the Netherlands and Belgium. With genuine EMA-approved Ozempic with a doctor's prescription and pharmacy dispensing, such complications are virtually ruled out.

What Go Leaner does to limit risk

Our BIG-registered doctors follow a protocol that limits the risks to a minimum. At every intake we carry out extensive blood tests (HbA1c, liver, kidney, thyroid, lipid profile) and check for contraindications (family history of MTC, pancreatitis, pregnancy).

During treatment we monitor monthly, adjusting the dose according to tolerability. We strictly follow the EMA titration schedule (4 weeks per step) and start at the lowest dose. If serious side effects are reported (persistent abdominal pain, severe vomiting, turning yellow), treatment is stopped immediately and the patient is referred.

All medication is dispensed via a Dutch pharmacy with EMA-approved Novo Nordisk products. No grey market, no 'research peptides', no imports from unknown sources.

Patients also have 24/7 access to their doctor via the patient portal for questions or concerns. We always advise contacting us immediately about unusual symptoms rather than adjusting the dose or stopping on your own.